Variable-geometry exhaust nozzle with sliding sealing flaps
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Solution Overview
Problem
Variable-geometry exhaust nozzles for jet engines face issues with leakage due to gaps between moving flaps, leading to reduced efficiency and increased noise, complexity, and high maintenance costs, while existing designs fail to maintain optimal performance across varying operating conditions.
Innovation Solution
A variable-geometry exhaust nozzle design featuring pivotally connected flaps with continuous sliding surfaces and an actuator system that maintains contact between flaps, preventing gaps and optimizing the nozzle's cross-sectional area, using a hydraulically actuated system with angled sliding surfaces to counteract jet stream forces, ensuring efficient gas flow and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable-geometry exhaust nozzle with movable flaps is used to vary nozzle exit area, then nozzle adaptability to different operating conditions is improved, but gaps between flaps cause leakage of exhaust gas and cooling air reducing nozzle efficiency
Solution Approach 1:
A sealing flap is introduced as an intermediary element between the movable flaps to prevent leakage. The sealing flap fills the gaps created by movable flaps during area variation, acting as a mediator that maintains sealing without restricting the area adjustment capability of the nozzle.
Solution Approach 2:
The nozzle structure is segmented into multiple independent components: movable flaps for area adjustment and a separate sealing flap for preventing leakage. This segmentation allows each component to perform its specific function independently - the movable flaps control area while the sealing flap maintains sealing.
2Adaptability or versatility
If multiple movable components are used in variable-geometry nozzle, then nozzle adaptability is improved, but device complexity increases making it expensive to design, manufacture, maintain and operate
Solution Approach 1:
The sealing function is merged with the existing movable flap structure. The sealing flap is integrated into the same mechanical system as the area-adjusting flaps, sharing common pivot connections and actuation mechanisms. This merging reduces overall complexity compared to having completely separate sealing and adjustment systems.
Solution Approach 2:
The movable flaps serve multiple functions: they adjust the nozzle exit area for adaptability and simultaneously work with the sealing flap to maintain sealing. This multi-functionality reduces the need for dedicated components, simplifying the overall structure.
3Adaptability or versatility
If gaps between flaps are allowed during area variation, then nozzle adaptability is improved, but leakage of exhaust gas generates vortices reducing nozzle efficiency and increasing noise
Solution Approach 1:
The sealing flap acts as an intermediary that fills the gaps between movable flaps during area variation. By maintaining contact with adjacent flaps, it prevents exhaust gas from escaping through gaps, thereby eliminating the source of vortices and noise while allowing full area adjustability.
Data Source
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AI summary
The present invention relates to a variable exhaust nozzle (14) for a jet engine (1) comprising a fixed structure (16), a plurality of flap means (18) being pivotally connectable to the fixed structure (16), actuator means (20, 20h, 24) being arranged to actuate said flap means (18) for variation of the nozzles (14) cross sectional area between a first position and a second position. The respective flap means (18, 24, 26) comprises first flap means (24) and second flap means (26) each comprising a sliding surface (22, 22´) arranged in continuous contact with adjacent flap means (18) during said variation. The present invention also relates to method for varying a variable exhaust nozzle (14) for a jet engine (1).